Thermally insulated hobbing machine



\\\\\\\\Y/////////////////////jl P 1943 w. F. ZIMMERMANN 2,330,167

THERHALLY INSULATED HOBBING MACHINE Filed Nov. 13, 1939 4 Sheets-Sheet 1lNVENTdR mm \\1 BY 77 ATTORNEY Sept 21,,f1943 w. F. ZIMMERMANN THERMALLYINSULATED HOBBING MACHINE Filed Nov. 15, 1939 4 Sheets-Sheet a unk kEH56 INVENTOR V ATTORNEY-" p 3- w. F. ZIMMERMANN 2,330,167

THERMALLY INSULATED HOBBING MACHINE Filed Nov. 13, 1939 4 Sheets-Sheet 43 1 V x n w i i: A a

i i I *3 i 1 0 9 12,115 i 5 f i I F R N l- {I}.

"3 Q m "3 f x INVENTOR ations in helix angle and pitch lin PatentedSept. 21, 1943 THERMALLY INSUIATED HOBBING William F. Zimmermann,Maplewoo'd, N. J., as-

signor to Gould & Eberhardt, Newark, N; jJ.,.a' I corporation o'f'NewJersey. I: '2,- a

' Application 5November 13, 1939, se ial No. 304,037

16: Claims.

The present invention concerns improvements in the construction andoperation of machine tools and relates more particularly to anim provedmethod and apparatus for hobbingtge'ars free from the errors introducedby changes .in

expensive replacement parts become necessary.

ByQ-thepr'esent invention, it has now' been made a possible to maintainand preserve uniform thermal conditions in the machinefthroughout thetemperature in Various elements of the machine organization, the efiectof which is to cause varie diameter from one face of the gear to theother. I

The primary aim of the invention is to-pree vent the heat generatedbythe driving elements of the machine from being transmitted "tofandfrom having any effect upon, other elements and members of the machinesuch as would change or otherwise distort a predetermined precisionrelation in alignmentofxthose members. JIn-the hobbing of gears, forexample and particularly .7

gears of relatively wide face and large diameter, several days ofcontinuous 'cutting. ;may be required to finish the, teeth of one gear.Extreme care and accuracy insettings and relations are essential in allphasesof the operation, not merely in the initial set-up of the machine,but throughout the hobbing operation on a given gear or set of gears;..And during the cutting operation the temperature from-night to day maychange as much as 20? or more.- i y The hobbing of large gears requiresmassive and extensive-machines, so extensive,,in fact,

that a warming up ofdrive motors,';bearin s,.v

shafts, etc. situated atone end of'the machine produces a correspondingdistortion in the frame in a particular region or zone which is not feltin more distant portion ofthe machine. Liliewiseblarge masses such asthebase off'themachine, stanchion, the gear blank itself, etc'jcool or Warmup very slowlyas compared to; the parts of lighter sections such asthelead screw, etc.

Knowing the coefficient of thermal expansion of ironito be .00006" perinch, per degree change in gear ,cuttingoperationand the error in theishedjproduc't. heretofor due to .such variations has been eliminatedllv When machines embody a inumber,of;relatively movableele'ments, such asme gear h'obbing machine, the importance andneedforiinitially establishing and: thereafter. maintaining perfect synchronism inmovements. and perfect align ment of the moving parts, cannot be over'esti mated. Heretofore .little or no regard has been given,.in thedesignfof machine toolsof this character, to the efie'cts of temperaturevariations on the precision relation of the several coacting elements.of the machine. The present invention further aims to renderavailable ama.- chine that isum'aintained free of distortion and unaifected byvariations in thetemperature of the main driving transmission elementsand motor to the end that ahigh degree or accuracymay be obtained andmaintainedjthroughout its per,

formance. l 1 V A further. aim of the invention is to improvetheoperation and maintain high standards of accuracy in the functioning,of a machine by estab- I lishing and ma'intaininga' predeterminedatmosphericcondition about the machine'as a whole and effectivelyinsulating closely related elements thereof .from external changes so asto render the Y criticallmembers of the machine immune-toe);-ternalvariations h 1 Heretofore hobbin'glmachines were customarily builtas complete self-contained machines with transmissions, motors, etc.built in and concentrated withinlthe main frame thereof. ,In 'attainingthe objectives of this invention it is protemperature, a 20 change inroom temperature will alone affect the bed of a 30 foot machineas muchas 1 of an inch- In consequence ofsuch non-uniform expansion andcontraction, pronounced changes .in alignment of parts and in theprecision relation between tool and work are brought about causingserious errors to be introduced in thefinishedproduct. I i

In the manufacture of high speed turbine gears for marine work thegreatest precision is required to produce gears capable of meeting thedemands and requirements placed upon'them. Y A very slight run-out in agear travellingat high speed Will cause excessive noise and highlyobjectionable vibration. and ma relatively shortxtime posed to constructthe'machineon entirelydifferent 1ines,'and to so. arrange thedriving-elemerits of the machine so that all fmaindrive shaftswandbearings therefor. are located exter-' nally'of the machine proper. Theheatj'generated by'such shafting and bearings 'asmiiysubse- ['que'ntly;develop as the tooling operatic-n progresses, will not therefore beiconfined to f or trapped Within, particular portions ofthemaprime frameand hence will notice localized.

Q'Ioward the same end, it is further proposed to' construct the drivemotor or'motors and change speed transmissionv mechanisms as a separateindependent unit and 'to isolate the unit from the j'main frame of themachine so that; the heat generated thereat is not transmitted; to themain The v ports an indexible cutter carriage l3 and rotatable cutter M.The base of the machine It) may be constructed in units such asillustrated at a, b, and c, of which the units a and c are stanchionbases and the unit b an indexible table base. A work table [5 rotatablymounted in the bearings provided in the base 0 is adapted to havemountea thereon the" workpie'ee ar'ifd rotate the same synchronouslywith the rotation and feed movements imparted to the hobs l4 and I1. "Asimilar cutter stanchion 56 is located at the opposite side of the workblank and the cutter H thereof is, in the case of cutting theherringsudden change in temperature. Overhead re;-

moval panels, sufficiently large to permit. the largest of workpieces tobe loaded upon and removed from the machine are also provided.

An enclosure of such character renders the machine immune to the efiectsof variations in external atmospheric conditions and alsoimmune to theheat generated by the maindrivernotoroi' motors and from within'th'egear box of the ma: chine. And byloca'ting one '01 moreair conditionin'g units in theenclo tire, the temperature and condition of theair about the machine'may be controlled and maintainedbonstant withinnarrow 1imit s., Such shafting and bearings as are necessary tojcondu'ct the power from-the outside of theenclos'ureflto'theseveraloperating elements of the inachine areashas been iii icated above,journaled outside r the main frame work'of. the machine pro-per, and aremaintained at a substantially uniform temperature by'continuouscirculation oflcon'ditioned air.

'By this invention it neither the heat gener' tedby various elements ofthe. power transmission, nor thatjof thebbhtinually'va rying atmosphere,has any 'ffctiipo'n the precision operation of a machinesoii'onstructedan'd once the "machine is setup one given precisionoperatic) its initialaecuiacy remains constant throughout the operationor a succession of operations.

Other objects and advantages will b "impart description a'iid -'ihindicated in the following i'part rendered apparent therefrom inconnection with'the annexed drawings. I To enable others skilledin'theart so fully-to apprehend the underlying features hereof that they mayembody the same in the various ways contemplated by this invention,drawings [dejpicting a preferred typical cOnstruction haVe been annexedas'a' part of this dis'closurearidfih such drawings, like characters ofreferencedefnote corresponding parts throughout "all "the views, "ofwhich:

. Figure 1 is a'side elevation of amachirieorganiiationfembodying thisinvention. Fig.2 is aplan view thereof illustrating ferred relation ofthe'main elements'of the v7 drive to the machine and to the enclosureforthemachine. L

Fig. '3 'isa vertical section t'aken along'filine Fig. 4 is a detailviewpartly in seCtitin'illhs .trating the external jmounting, to both basestanchion, of thbe'aririgs for running shafting.

Fig. 5 is alin'e diagram of the entireld riv'e. Referring to theillustrated in connection with a' gear hobbing niachine which comprisesa base it! uponfwlii'c'h is mounted for ti 'nsl'a'tionl toward or awayin the workpiecefW. a cutten'stanchion "H. v

The

front of the stanchion has mounted'thereoma I V 7 "r5 fromthere-"through bevel gears- 31 to a vertical verticallytranslatablecutter slide 12 which siip- 'will be apparent that 1 bone gear arrangedto feed up, in synchronism withthe down feed of the cutter I4 during the.yope'ration of cutting teeth on its respective portion of the workblank W.

With reference to Fig. 5 of the drawings, the main drive to the worktable and to both cutters is derived from a main motor 20 (in thisinstance tony-P.) which oper tes through thechenee speedmeehemsmihdicaiea, to brave-a rhain cutt'r dr'ive shaft Z La rnaiz'YuttT feed s'haftfl 31nd a rnain table ifid'e'f'sihaft 23. It willbe-"lll'ii- 'der'stood that the reretrve 'spe'eds a'nd feeds of theseelements are ii'rdpei'lybb-oidii'iatfi to effeet the pro er utting ofteeth on the work x'blank. I i

A pair of bevelfga'r s 24 divides "the cutter drive into two bfanches il -24 -'e"ach branch leading eventually 'ihtb diie hr-theycutteicarriages fdrtiiivin'g th'ehlib. Similarly a pair of bevel"gears-25 divides thefeut't'r feed drive into two: branches 25, 25'"e'ach leading eventually to the feed mechanism of the tool slides 12.

In thepres'erit tatable worktable, there aife *pfer(:"faloly two pair'-allel arranged driveathieflir; atrbiighi'ng tli ive through wor'm ge'a rwhen 25, wor'm geai- 21 and "drive 'shaft 23, and a finishing "drivethrough wormfgear;whel fiit worih gear 29 and drive "shaft 23 'lihist'abl'e drive is described and e3:- plaine'd' 'o're fiill y in my'opehkiirig application, Serial No. zeogosp'e'na iiedfiiot, therefore, be"explaineii'iniietail except t-oState-thatthe table is rotatedsolely by-eitherfthe roughing'drive or the finishing drive and heve'rWiy' both"of 'said drives simultaneously. 1

p 'will be lbb'served fio'iii Figs; '2 end 5, the shafts "Zitaand fi and*Z IWa'n'd 25 and-15 "heat that' 'eiy qeveie atthe heal-me debates s rigt -f-siia t a. joiirnalsffor t f-"tet a 'gears"31. are providedbyan-externalbracke 39, also secured to the translatable fstanchion l1-.

A'second pair of bevel gears--40 {iourn'a'l'e'dinthevertically"translatable tool slide lz transmits the, 1

motive power to thehob I4 in the known manner. The cutter feed is fromshaft through bevel gears 4 l, to splined shaft dzthencethrough 'bevelgears 43 to a short vertical shaft 44 to'bevel.

gears 45 on a horizontal shaft 46. All journal bearin s for the gearsand shafting Ill-46 are located externally of theframes-"as shown; in'Figslland2.

' The horizontal shaft-45 transmits the power to an external verticalshaft 4'l, journaled atthe opposite side of the machine, through I have]gears 48. From shaft ll-the power enters the machine through gears Mandasingle" shaft 50 and-drives the cutter feed screw 5l.-nc 2 i The driveand feed of thecutter l1 onthe stanchion to the lefttin Fig. 2,;is.substantially identical with that' just .described and a':descrip-.tion'of one is thought to :be sufiicientr. It will be observed, however,that inall instances, all

of the bearings for the several Jdriveshafts in dice-ted, and allbearingsfor the various power transmitting gears whether they are fixedin space or translatable are journaled in brackets secured to theexternal surface of the mainframes of the machine. Such bearingsandshaftingare,

the moving parts. thereof such as wouldndistort such parts and bringabout a corresponding error in the precision cutting ofthe'gear teeth. J

The bearings for the table driving worms ,2! and 29in theirrespectiveshafts are provided by a separate bracket bolted to thetablebase b and any warmth that may. develop at such ree gions is nottransmitted .to the table or. table base, except indirectly.v v 5 Apower drive so arranged has the further advantage that all of theprimary power transmitting elements are conveniently accessible'forsubsequent replacement' or repair without any mate rial dismantling ofthe machine as a. whole. Moreover, the machine so designed lends itselfreadily-adaptable to manufactureon the unit principle and shipped orotherwise transported in a like manner and thereafter convenientlyjassembled at the location or site selected. A i In addition to provisionshereinmade for conducting and, dissipating the. heat that may de velopat the externally mounted bearings and journals for the several maindrive shafts, it is further proposed to enclose the entire machine, withthe exception of the main transmission house ing and drive motors, inanenclosure byrneans of which the machine proper may be isolated fromthe atmosphere generally preva-ilinginany'plant. Figs. 1 and2-illustrate a preferred form'of en'- closure forthe machine properwhich comprises fourside walls 69, 6|, 62, 6 3, and a'roof 64. The wallsand roof'of the enclosure are constructed of a thermal insulatingmaterial of a' suitable character and is intended'to be permanent innature. p 7

At convenient locations of the enclosure, pref; ably at the frontend'and at the rear of the machine, double door entrances A and B {areprovided to per'mitaccess. to the machine byfone "or more operators;Thedoubledoorarrange;

. sure;

ment at the entrances, located at least at two point's abo-utthemachine; aiford convenient access thereto and at the same timeprevents too rapid-or sudden T changesin the temperature or condition ofthe atmosphere within the erlclo- The lower portions of therear'wall 62of the enclosure follows the general outline ofthe'transmission housing"G and drive-motors M, m, as illustrated at 62' in Fig. 2. The wa1ls'62!rise from-the floor to fa, point clearing the motors and transmissionhousing and are overlaid by a removable cover section 65 which extendsto the outered ge of the'enclosure, as indicated in Fig. 3, where itjoins with the main vertical wall 62.

Recessed'vertical walls 62" are also removable to permit the assemblingof the several machine units and to render the making of/subsequentadjustments oralterations to the mechanism possible. The roof portion 64of the enclosure is formed with o'n'eior more removable panels 64' whichmay be displaced so-ithat, the workpiece W may be moved therethro-ugh byan overhead crane. All switches and control relaysforgoverning theaction of the machine arelocat'ed away from the machine in acontrolpanel box 15 which maybe built in or attached to the enclosure wall 66in a .IJDSitlOHJCOllVBHli-lflt130' the operator's nor,- mal workingstation. t

In thisway the main frame of the I may be isolated from the maintransmission and heat produoingelements in a practicalandeffectiveymanner and the transmission itself rendered freely"accessible for, the purpose of making changes in" cutter speeds, feedsand, table movements, from the: outside of. the enclosure. Any heatgenerated by the transmission and particularly the heatgiven offbythemaintmotors is effectively isolated fromythe main machine andfthereis consequently nodanger of any localized expansion or'contractionof members or elements of the, mainmachine as, would disturb theprecision relation of the cutter and the work.- If de. sired a separateenclosure, for-the transmission atmospheric condition, air conditioningunitsindicat'ed at it, H ,are proposed for maintaining a continuouscirculation of air at a controlled temperature about the machine. Thetemperature, of the machine itself may thereby be maintained at asubstantlallyconstant value and may be depended upon, irrespective ofthe tempera-; ture or condition of the external atmosphere; to performits intended operation continuously without variation. It-is important,however, that the air velocityirom the ducts supplying the constant,temperature be sufficiently high, quickly to raiseiorlowerthetemperature ofthe object, such a ia work blank or fixture,brought into the room, and tomaintain. not only a constant temperaturebut an equal temperature throughout the room ISu'cha controlledcirculation of air about the f machine, in addition to carrying offanddissipating any, temperature rise at the several bearing brackets,also tends'to carry off anddi'ssipate heat they may develop by reason ofthe action of the cutter inperforming the tooling operation.

The drives hereinbefore explained constitute the main drives to thecutter and work table and normally are in continuous operation; Themachine, however, embodies still further power transmissions forefifecting a power adjustment "of certain of the 'majorelements. Forexample, a stanchion traverse-motor l6 secured to the outer-end of eachof the stanchion bases {see Fig. 1), is provided :for adjusting thestanchions Hcand l6 towardand .from the workpiece, of the motors l6operate through "an independ ent train of mechanismindicated generallygas 11 and serve to drive the stanchion feed screw shaft 7 ing indicatedat'82 with the feed shafts and 25 for traversing both, tool carriagessimultaneously when desired, V

,As such motors are us d only infrequently and normally are at restthroughout the actual tooling operation, they do not in themselvesconstitute a heating plant or plants which has any material efiect uponthe machine structure as a whole. 1 Lubricatingmotors such as indicatedat 83 (see Fig. 2) which continuously operate to forcelubrrcant underhigh pressure to all bearing and :sliding surfaces of the machine, andgenerate appreeiable heat in driving ahigh pressure lubricant pump, arealso located outside of the thermalenclosure so the variation intemperature thereof has no effect .upon the machine proper.

A cutting" lubricant and cooling motor 84 supplies a copious quantity oflubricant at low pressure to the respective cutters and-doesinot becauseof its low pressure duty overheat. Such amotor may, therefore, beat thesump 85 adjacent the main frame of the machine.

1 Without further analysis, the foregoing will'so fully reveal the gistof this invention that others can, by applying current lmowledge,readily adapt it for various utilizations by retaining one or more ofthe features that, from the standpoint of the prior art,fairly-constitute essential characteristics of either the generic orspecific-:aspects of this invention and, therefore, such adaptationsshould be and are intended to be, cornprehended within the meaning andrange of equivalency of the following claims. I Having thus revealedthis invention, I claim as new and desire to secure the followingcombinations and elements, or equivalents thereof, by Letters Patent ofthe United'States:

1. A machine tool subject to error incident to temperature changescombining a main frame,

a tool support and a work support mounted thereon, and power means foractuating the tool comprising a plurality of shafts, bearing means forjournaling said shafts to the external surface of said mainframe-andspaced therefrom, a

single shaft connecting said externally mounted shafts to the ultimateelements of the'tool actuating mechanism,'a main drive and change speedtransmission housing physically separate from said main frame andlocated ata distance-theretant locationiof the housing-fromthe mainframe and .the external mounting of the power shaftins Onsaidi ame.

2. A 'machine tool combining two upright standards, .a translatable toolcarriage-mounted upon each of, said standards, a tool rotatablymounted-"in each'ofsaid carriages, a work support commonfto both-of said:standardsand power means separate from the said standards fortranslating said carriages and for rotating said tools comprising amainpower transmission unit physically spacedir'om anddistantly locatedwith respect to said standards, said distant transmission unitincludinga prime mover and mecha mm for determining the rates of toolrotation wand carriage translation relative to the workfrom, saidhousing having mechanisms therein i for determiningthe relative rates ofmovement between the said tool andsaid work support, and a relativelylong power shaft connection extending from said mechanisms of saidseparated transmission to said externally journaledshaftnight the mainmachine for actuating said tool whereby any rise in temperaturedeveloping .at the said physically separate transmission housing isdissipatedin the, airby virtue of the dis- :piece and power shaftconnections extending iromisaid distantly located ,main transmissionunit to each of :said tool andcarriages of the machine for :actuatingthe same.

53..A machine tool. combining two upright standards, :a "verticallytranslatable tool carriage mounted upon each of said standards, a toolrotatably mounted in each ofsaid carriages, a single work supportacommonto both of said standards,;and :a :common power means fortranslatingsaid carniages and forrotatingsaid tools consisting of amotor, change peed transmission mechanisms, and a transmission housingfor said power rmeans physically separate from and distantly flocatedwith respect to said standards and work support; power transmittingmeans connected to the said transmission mechanisms of saidlseparatehousing and with the said movable elements of said-standards andtraversing 'the distance therebetween for efiecting relative movementbetween the tools and the workpiece at a elected rate; saidspacedrelation of said power means and said standards serving as means' forthermally isolating the said motor, transmission andtransmission housingfrom both or the said standardsnthereby to maintain the standards andwork support free of the effects of temperature changes occurringiat thedistantly located motor and .change speed mechanisms during theoperation of thepower means.

4. A machine. tool in which distortion of the members due to temperaturevariations introduces errors in the finished work combining ,a mainframe adapted to support a workpiece and a tool in cooperative precisionrelation; aphysi- 'cally separate anddistantly spaced main powertransmission,'said transmissions including speed ratiodeterminingmechanisms for efiecting relatlve movement betweensaid tooland workpiece at-apredetermined rate to perform a tooling op-veration,*relatively'long power shaft connections traversing the distancebetween said transmission and said main framefsaid long shafts providingthe only power transmitting coupling between the. mainframe and saiddistant'transmission unit", bracket means for journaling 'saidconnections "tothe exterior surfaceof said frame i Spaced relationtherewith; said bracket means and said spacedmelationlof said main frameand main'power transmission cooperating to facilitateidissipation of anyheat radiating from said transmission .or generated at said externaljournal' bearings and thereby maintain the machine as a whole at apreselected temperature throughout the jtoo'lingoperation.

, '5. A machine tool having 'in combination a mainl-frame; atoolcarriage mounted thereon, altool.rotatablyimountedLin said carriage, and

power meansv for feeding said carriage and for rotating saidtoolcomprising a carriage feed train of mechanismsand a tool drivingtrain of mecha- I feed, and relatively long power shaft connectionsbetween said transmission unit and said exter-r nally journaled shaftingof the machine for actuating said tool and carriage.

6. A machinetool combiningga.standar d, a

translatable :tool carriage mounted thereon a tool rotatably mounted in;said carriage, and means for translating saidcarriage and for rotatingsaid tool in timed relation comprising-a plurality of, shafts, bearingbracket means for journaling said shafts to the external surface of saidstandard, a singleshaft connecting one of said externally mountedshafts. to the ultimate elements of the tool rotating and to theultimate elements of the carriage translating-mechanism respectively, amain transmissionhousing separatefrom said standard and located at adistance therefrom, said transmission housing having journaled therein aplurality of change speed mechanisms operativelyrelatedas to coordinateI the rates of movement of said tool and said carriage; andrelativelylon power-shaft connections between the change speed mechanisms of saidmain transmission and said externally journaled shafting of the machinefor actuating said tool and carriageat rates determined by the saiddistant change speed mechanism, said long power shaft connectionsaffording the only physical connections between the main machine and itstransmission.

7. A machine tool inwhich distortion of: the

members due to h'eatingfintroduces errors in the finished. workcombining ga main frame adapted to support a. workpiece and a tool incoopera tive' relation; a physically separated anddis tantly spacedpower transmission housing including a drivingmotor main drive gearingfor effecting relative movement between said tool' and work piece atselected speedsto perform a tooling operation; power shaft connectionsextending between said housing and said main frame, bearingbracket meansfor journaling said shaft connectionsrexternallyof said frame and spacedtherefrom, and "means including theair gap between saidmainframe andsaid separate" and distant transmission for thermally insulating saidtransmission housing from-said main frame to isolate said frame andparts supported there on from the heat generated at said transmis sionhousing; and shaft means also iournaled in said bracket for conductingthe power delivered to the machine through said long shaft connectionsto said tool and workpiece.

8. A machine tool combining a main frame, a

work support rotatably mounted thereon, a tool slide translatablysupported on said frame, and a tool spindle rotatably journaled on saidslide; power means for driving said work support, tool slide, andtool'spindle comprising a physically said tool spindle.

separatedpower transmission including a main drive motor-andpowerdividinggearing. located at a distance from said main frame, apartition wall between said transmission andv said mainframe forinsulating the latter from-the heat generated at and by the-former; andmeans comprising a work table drive shaft, .atool slide drive shaft, anda tool'spindledrive shaft extending through said partition wall andseverally com nected at one side thereof with related elementsofsaid'transmission and at the other side with gearing journaled on;saidmainframe for transmitting motive power from thephys'ically spacedtransmission to said work support, tool slid, and

tool spindle espectively, at .ratesjdetermined,by-

said power dividing means.

9. Amachinetool, combining a main frame, a work support rotatablymounted thereon; a roe, tatableftool spindle alsosupportedon said frame;power means'for driving saidwork support'and tool spindle/gcomprising aphysically. separate power transmission located at a distance from saidmain-frame, said, transmission including a main driving motor, change ofspeedand'reverse ingmechanisms, and 'atleast two terminal drivenelements a'partition, wall between said trans:

mission and said main frame; and meanscom-j 7 ong shaftextendingfthrough said partitionand connected at one end with] one of;said, terminal elements of the transmission prising a, relatively atoneside {of the partition and at the other,

end with,gearing-journaled on said mainframe at'the other side; of thepartition for transmit; ting motive power from the spaced transmissionto, saidwork supportj and v a second relatively long shaft extendingthrough said partition and connected at-one end tothe other of saidtermi nal drivenelernents and at itsother end- -with gearing journaledonsaid main frame for transmittingl motive power from said transmissionto] 10., A;machine ,tool in which distortion -oofthef members oneto"temperature'variations creates errorslin the, finishedworkncombiningja main framgeqadapted to support a rotatableWorktaf-ibleand atool in cooperative precision relation;

a' separate and distantly spacedj main ,power transmission unitincluding a main drivermotor forgeffeotingwrelative movement betweensaidtool and workpiece to perform a tooling operation; fa

first setwof power shaftccnnctions traversing the distance between s'aidrnain frame and the said 'spaced transmission unit; means at the mainframe end of said power shaft connections for:

conveying the-gpower from said connections to said: toolincluding aplurality of shaftssupported exteriorly, of and spaced fromthe'said mainframen'and a: second set'o'f power shaft'connections traversingtheyspace between saidpower transmission andsaid mainframe for.drivingsaid work table, said spaced relationvof the main frame and'th'e powertransmission unit and the exterior andspaced mountingpfsaid shafts pro;

viding air gap means'efiective to absorb and dissipate the heatgenerated at said transmission.

11. In a machine tool havinga rotatable Work table, a rotatable andtranslatable tool spindle,

means for maintaining a precision relation bev tween said elementsuneffected by heat generated 1 at the power source comprising a mainframe adapted to support said work table and tool spindle in cooperativeprecision relation; a physically separated and distantly spaced mainpower transmission unit including a main drive motor for operating saidtool spindle andwork table to perform a tooling operation; powerconnections traversing the distance between said main frame and saidpower transmission; means at the main frame end of said powerconnectionsfor transmitting the power to said tool spindle and to said rotatabletable including a plurality of shafts supported exteriorly of and spacedfrom the said main frameto provide heat dissipating air gapstherebetween; and means at said distantly spaced transmission unit forcoordinating the movements of the work table to themovements of the toolspindle. i

12. A machine tool in which heat generated by the main drivingtransmission creates errors-in the finished work combining a main frameadapted to support a workpiece and a tool in cooperative precisionrelation? a physically separate and distantly spaced second frame forsupporting and housing the main driving transmission for the machine,said transmission including a main drive motorffor effecting relativemovement between said tool and workpiece-to perform atooling operation;a power shaft tray ersing the distance between said mainframe'and saidsecond frame for transmitting motive power from the latter to theformer; means at the 'main frame end of said shaft for transmitting thepower to the tool includinga plurality ofshafts each supportedexteriorly of andspaced from the said main frame; and adjustable meansat the other end of said transmitting shaft and sit-' uate mechanicallybetween said motor and said eridof theshaft for predetermining the rateof movement of said tool in relation to the workpiece. a j 13. A gearhobbing machine tool having a tool spindle and work support adapted tobe power driven in correlation, the combinationof a main frame forsupporting said spindle and work support in precision tooling relation;a power plant for driving said spindle and work'support comprising ahousingphysically separate from said mainsupporting frame and situatedat a distance from said main frame; a barrier wall "eX-' tending betweensaid main frame and said housing, said barrier wall being spaced fromsaid main frame as to afford a substantial air gap therebetween; andrelatively long shaft elements operatively connected to the power planton one side of said barrier wall and with said main frame and thespindle and work support thereon on the other side of said barrier wall,said longshaft elements extending through'the barrier wall andtraversing the'air gap between the said barrier and the main frame, saiddistant locationfoi the power transmission, long shaft elements; barrierwall, and air gap aifording'meansfor'keeping the heat generated at'saidpower transmission away from the main frame of the machine thereby tomaintain the main frame and the precision relation between thetool'spindle and. work support free of the effects thereof. b

14. A machine tool in which distortion of the tool or work supportingmembers due to localized temperature variations creates errors in thefinished work combining a main frame organiza tion adapted to support aworkpiece and a tool in cooperative precision relation; a coactingseparate and physically separated main power transmission organizationcomprising-a main drive motor and speed change gearing for chattingrelative' movement between the tool and workto perform a toolingoperation; a partition wall extending between said physically separatedorganizations, said wa1l bei'ng spaced from each of the separatedorganizations and adapted thermally to shield thesaid main frame membersfrom the heat genera'ted'at said separated power transmission; andrelatively long shaft means extending throughsaid separating partitionwall for conducting motive power from the main drive motor and speedchange gearing situated on one side of the separating wall to the drivenelements of the main'frameorganizationsituate on the other-side of saidseparating wall. 15. A machine tool embodying at least two elementsadapted to be power driven and main-- tained in predetermined precisionrelation combining a first frame member for's'upporting'said elements; asecond frame member spaced therefrom, power "dividing and ratedetermining means mounted to said second frame member,

a source of motive power also spaced from said first frame member common'to said power dividing and rate determining means for driving same, andtwo sets of power transmitting-means connected; at their one ends tosaid elements on said first frame member and at their other endsto saidpower dividing and rate determining'mean's, said connections traversingthe space between said"two spaced frarne memb'ers whereby the heatgenerated at the onefhas little or no elfect' upon the precisionrelation of the elements supported 'on the other. V i iii A" machinetool combining" a main support; at least twome'chanismsjournaled'thereto adapted to be power driven in synchronism, a secondsupport physically separate from said main support, ratio determiningand correlat ing mechanisms for the said mechanismsof the main supportjournaled to said second support, and at'least two power transmittingconnections extending from the respective ultimate elements of saidratio determining and'correlating mechanisms of the second support totherespective initial elements of said mechanisms of said main supportand traversing the distance between said supports fortran'smittin'gpower from the: synchronizing mechanism to the mechanisms to be drivenwhereby the mechanisms of themain supportare synchronously driven andunaffected by temperature variations occurring .at said second support.v

' 'WILLIAM F. ZIMNLERMANN;

